Lock means for telescopic firearm bolts



Nov. 22, 1960 A. J. LIYZZA LOCK MEANS FOR TELESCOPIC FIREARM BOLTS Filed Jan. 22, 1959 all; law? 7 INVENTOR. Alheri J- Lizzu United States Patent Ofiice 2,960,917 Patented Nov. 22, 1960 LOCK MEANS FOR TELESCOPIC FIREARM BOLTS Albert J. Lizza, Willimansett, Mass., assignor to the United States of America as represented by the Secretary of the Army Filed Jan. 22, 1959, Ser. No. 788,473

2 Claims. (Cl. 89-190) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to firearms and more particularly to bolt assemblies therefor of a telescopic type.

It is an object of this invention to provide for bolt assemblies, which include a carrier slidingly disposed in a firearm receiver and a bolt telescopically mounted in the carrier, a pivotal pawl for releasably locking the carrier and bolt against relative longitudinal displacement from a fully extended relationship.

It is another object of this invention to provide such a locking pawl which may be accurately timed for actuation to a lock and an unlock position according to the position of the bolt relative to the receiver.

It is a still further object of this invention to provide such a locking pawl which is maintained in the lock position by the rolling engagement thereof with the inside wall of the receiver.

It is still another object of this invention to provide such a locking pawl which is controlled at all times during the reciprocation of the bolt assembly by the path in the receiver along which the pawl rollingly moves.

It is another and still further object of this invention to provide such a locking pawl which is simple in construction and positive in operation.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. l is a longitudinal, partially cross-sectioned view of a firearm receiver showing the bolt telescoped into the carrier and in a locked battery position and the locking pawl in an unlocked position; V V

Fig. 2 is a view similar to Fig. l but showing the bolt extended in the carrier and the locking pawl in the lock position to prevent the telescoping of the bolt into the carrier; 7

Fig. 3 is a view taken along line 3--3 of Fig. 1;

Fig. 4 is a view taken along line 44 of Fig. 2;

' 'f Fig. 5 ,is aview taken along line;5'5 of Fig; 3;'and

Fig. 6 is a view takenalong line 66 of Fig.4

Shown in the figures is a cylindrical firearm receiver 14 to the front end of which there is mounted a barrel 16 with an extension member 18 mounted to the breech end thereof. Slidingly inoun t ed in receiver 14 is a" bolt assembly 20 including a carrier 22 which has sliding engagement with the inside wall of the receiver and a bolt 24 which is telescopically mounted in an axial bore 26 in the carrier so as to lie in an extended or retracted position relative thereto. Bolt assembly 20 is reciprocally actuated by an operating rod 28 which is disposed so as to drive carrier 22 rearwardly in receiver 14 by forces produced when a cartridge is discharged in barrel 16. Bolt assembly 20 is returned to battery position by a pair of springs 30 which are disposed in engagement with the rear end of the carrier so as to be energized during the recoil movement thereof.

Provided on the front end of bolt 24 are opposing bayonet lugs 32 which are rotatingly engageable with mating bayonet lugs 34 in extension member 18 to releasably lock the bolt against rearward displacement from battery position. Bolt is rotated to and from the lock position by the sliding engagement of a follower 36 mounted thereto with a helical slot 38 in the wall of bore 26. Slot 38 is so formed that bolt 24 is rotated to the lock position during forward movement of carrier 22 relative to the bolt and is rotated to the unlock position during rearward movement of the carrier relative to the bolt.

In order that carrier 22 will have full longitudinal travel relative to bolt 24 after the bolt reaches battery position and bayonet lugs 32 on the bolt will be received between the bayonet lugs 34 in extension member 18 as the bolt goes into battery, a pawl 40 is mounted, as hereinafter described, to the carrier to releasably engage the bolt for preventing the relative displacement of the carrier and bolt from the fully extended relationship thereof when traveling together in recoil and counter-recoil strokes.

Pawl 40 is substantially triangular in configuration with a dolls head 42 extending forwardly from the base thereof. Provided in the upper apex of pawl 40 is a longitudinal slot 44 for receiving a roller 46 which is rotatably mounted on a pin 48 transversely mounted through the pawl so as to pass through such slot.

Pawl 40 is mounted in a recess 50 which extends radially through carrier 22 from bore 26. Extending forwardly from the outer portion of recess 50 is a semi-cylindrical portion 52 which rotatably receives dolls head 42 to provide a bearing for pivotal movement of the pawl between a lock and an unlock position.

Dolls head 42 is maintained in engagement with semicylindrical portion 52 by the sliding engagement of the rear end of pawl 40 with the rear end of recess 50 and such rear end is arcuately contoured accordingly.

With dolls head 42 received by semi-cylindrical portion 52, the base portion of pawl 40 inclines inwardly and rearwardly from such semi-cylindrical portion so that the rear apex of pawl 40 extends angularly into bore 26 when roller 46 is in engagement with the inner wall of receiver 14. That portion of such rear apex which is extendible into bore 26 will hereinafter be referred to as tongue 54. Provided on the rear end of bolt 24 so as to be engageable by tongue 54 is a cam portion 56 whichinclines outwardly and forwardly at an angle corresponding to the inclination of the base of pawl 40. Pawl 4ii is disposed so that tongue' 54 is engageable with cam portion 56 when the bolt is extended in carrier 22 and thereby such bolt and "carrier are 'preven'ted'from telescoping while traveling together to and from recoil position.

7 In order to pivotally displace pawl 40 to permit forward movement of carrier 22 relative to bolt 24 after the bolt stops in battery position, a channel 58 is provided along the inner wall of receiver 14 to receive roller 46 during such relative travel of the carrier. Whereby; pawl 40 is pivotallyactu at ed to retract tongue 54 into recess 50 and out of engagement with bolt 24 by the camming engagement of cam portion 56 with tongue 54 and the forward bias of the springs 30.

The rear end of channel 58 is terminated by a ramp 60 which extends inwardly and rearwardly from the base of such channel to the inner wall of receiver 14. Ramp 60 is so positioned that pawl 40 is engageably pivoted thereby to the lock position when carrier 22 is moved rearwardly relative to bolt 24 to where the bolt is fully extended in the carrier. The position of ramp 60 also determines the point in the forward travel of bolt assembly 20 where pawl 40 is actuated to release carrier 22 for the continued forward travel thereof after bolt 24 is stopped in battery position. g

Thus, when bolt assembly 20 is in locked battery position and a cartridge is fired in barrel 16, forces from the discharge are transferred through operating rod 28 to carrier 22 which is accelerated rearwardly thereby. Bolt 24, however, is held against rearward displacement by the engagement of the bayonet lugs 32 and 34 and therefore carrier 22 moves initially relative to the bolt. During suchrelative movement, slot 38 moves along follower 36 to rotate bolt 24 to the unlock position for the disengagement of the lugs 32 and 34. Also during such relative movement, roller '46 travels along channel 58 whereby pawl 40 is positioned so that tongue 54 is clear of bore 26 and therefore does not interfere with the 'rearward travel of the carrier. However, when follower 36 approaches the rear end of slot 38 and bolt 24 is fully extended in carrier 22, roller 46 engages ramp 60 where- 'by pawl 40 is pivoted to the lock position wherein tongue 54 is positioned for engagement with cam portion 56 to prevent the bolt and carrier from telescoping. Tongue 54 is held extended into bore 26 as bolt 24 and carrier 22 move together to and from recoil position by the engagement of roller 46 with the inside wall of receiver 14.

When bolt 24 reaches battery position during counterrecoil travel, roller 46 is positioned adjacent ramp 60 whereby, through the forward bias of the springs 30 against carrier 22 and the camming engagement of tongue '54 with cam portion 56, pawl 40 is pivotally actuated to disconnect the carrier from the bolt so as to be free for continued forward travel. During the following movement of carrier 22 relative to bolt 24, slot 38 is moved slidingly along follower 36 to rotate the bolt to the lock position for the engagement of the bayonet lugs 32 and 34.

From the foregoing it is clearly apparent that there is provided herein a means for releasably locking a telescopic bolt in extended relationship which may be accurately timed as the locking pawl directly connects the bolt to the receiver and therefore is actuatable at a specific point in the travel of the bolt respective to the receiver and which is controllable at all times during the travel of the bolt assembly by the path in the inside of receiver '14 along which the pawl engageably moves so that the pawl is positive and accurate in actuation. It is also apparent that the locking device -is both simple in design and rugged in construction.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In a firearm provided with a receiver and a reciprocable bolt assembly including a carrier slidingly disposedin the receiver, a bolt telescopically mounted in a bore through the carrier and cam means for rotating the bolt to and from a lock position during movement of the carrier relative to the bolt when the bolt is in a battery position, the combination of a recess extending radially through the carrier from the bore, a pawl substantially of triangular configuration mounted in said recess for joint engagement with the bolt and the inside wall of the receiver, a dolls head portion extending integrally forward from said pawl for rotational engagement with a mating portion in said recess to pivotally support said pawl for displacement between a lock and an unlock position, a tongue portion of said pawl extendible into the bore when said pawl is in the lock position and retractable into said recess when in the unlock position, a cam portion disposed on the end of the bolt for engagement with said tongue portion when said pawl is in the lock position and the bolt is in an extended position relative to the carrier to prevent a telescoping of the bolt and carrier, and integral means in the receiver disposed for operational cooperation with said tongue portion and said cam portion for controlling the pivotal displacement of said pawl between the lock and unlock positions whereby the carrier is unlocked from the bolt to permit longitudinal movement of the carrier relative thereto when the bolt is stopped in a battery position and the bolt and carrier are prevented from telescoping when traveling together.

2. In a firearm provided with a receiver and a reciprocable bolt assembly including a carrier slidingly disposed in the receiver, a bolt telescopically mounted in a bore through the carrier for reciprocation therein between a retracted and an extended position and cam means for rotating the bolt to and from a lock position during travel of the carrier relative to the bolt when the bolt is in a battery position, the combination of a pawl substantially of a triangular configuration mounted in a recess extending radially through the carrier from the bore and disposed for joint engagement with the bolt and the inside wall of the receiver, a dolls head extending forwardly from the base of said pawl for rotational engagement with a mating portion in said recess to pivotally support said pawl for actuation between a lock and an unlock position, a roller mounted to said pawl for rolling engagement with the inside wall of the receiver to maintain said pawl in the lock position, a tongue portion of said pawl extendible into the bore when said pawl is in the lock position, a cam portion disposed on the rear end of the bolt for camming engagement with said tongue portion when said pawl is in the lock position to secure the bolt in the extended position relative to the carrier and to press said roller into engagement with the inside wall of the receiver, a channel disposed longitudinally along the inside wall of the receiver to receive said roller when the bolt is stopped in a battery position for displacement of said pawl to the unlock position and thereby permit longitudinal movement of the carrier relative to the bolt, and a ramp terminating the rear end of said channel, said ramp being disposed so as to cam said roller from said channel into engagement with the inside wall of the receiver for actuating said .pawl to the lock position when the bolt is moved from the retracted to the extended position thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,035,539 Dicke Mar. 31, 1936 2,771,819 Morse et al Nov. 27, 1956 FOREIGN PATENTS 67,568 Norway Mar. 13, 1944 

